1. Field of the Invention
The present invention relates generally to transducers for inducing vibrational signals in an elastic medium, and more particularly, but not by way of limitation, it relates to an improved construction for a relatively high frequency transducer for generating seismic waves in the earth.
2. Description of the Prior Art
The prior art includes hydraulic vibrators having drive cylinders and biasing cylinders as is illustrated by U.S. Pat. No. 3,745,885 issued to Fair et al. on July 17, 1973. The Fair et al. apparatus is constructed for operation in normal frequency ranges of approximately 2-80 cycles per second. Yet another patent of particular interest is U.S. Pat. No. 4,106,586 in the name of Stafford. This teaching provides a vibrator assembly wherein the cylinder end sleeves are adjustable between two extreme positions to either shorten or lengthen the hydraulic cylinder. The present invention provides a form of apparatus generally similar to that of Fair et al. but suitable for a much higher operating frequency range up to and exceeding 250 cycles per second.